【2016.4.27】二维数组分组：按照一个键值，按照多个键值

<?php
$arr = array(
    array(‘id‘ => 1, ‘name‘ => ‘seu‘,‘brand‘=>‘临‘),
    array(‘id‘ => 1, ‘name‘ => ‘seu‘,‘brand‘=>‘临‘),
    array(‘id‘ => 3, ‘name‘ => ‘njupt‘,‘brand‘=>‘兵‘),
    array(‘id‘ => 3, ‘name‘ => ‘njupt‘,‘brand‘=>‘斗‘),
    array(‘id‘ => 1, ‘name‘ => ‘seu‘,‘brand‘=>‘者‘),
    array(‘id‘ => 1, ‘name‘ => ‘seu‘,‘brand‘=>‘皆‘),
    array(‘id‘ => 1, ‘name‘ => ‘seu‘,‘brand‘=>‘皆‘),
    array(‘id‘ => 2, ‘name‘ => ‘peking‘,‘brand‘=>‘阵‘),
    array(‘id‘ => 2, ‘name‘ => ‘peking‘,‘brand‘=>‘阵‘),
    array(‘id‘ => 3, ‘name‘ => ‘njupt‘,‘brand‘=>‘兵‘),
);

现有如上的二维数组

要求1：按照id分组

实现方法：

<?php
foreach($arr as $v){
    $newArr[$v[‘id‘]][] = $v;
}
return array_values($newArr);

要求2：按照id和brand分组

实现方法：

foreach($arr as $v){
    $newArr[$v[‘id‘].$v[‘brand‘]][] = $v;
}
return array_values($newArr);